The present invention relates to a medicine-containing syringe (pre-filled syringe) in which two kinds of medicines are separately sealed. More particularly, the present invention relates to a pre-filled syringe which has a simple construction, can be produced easily, can store two kinds of medicines, for example, a first solution and a second solution or a solution and an powder reliably, separately, and for a long time, allows uniform and rapid mixing the two kinds of medicines to be accomplished in administering to a patient or mixing to other medicine, and can be used sanitarily and conveniently.
To mix medicines with each other, medicines accommodated in ampoule bottles or vial bottles are sucked up with a needle and then mixed each other. To inject a medicine to a patient, the medicine is sucked up with a needle. In recent years, to prevent microbism and foreign matter-caused pollution in an injection time or medicine-mixing time and reduce time and labor, widely used are a packed syringe into which sterilized medicine has been filled and a packed pre-filled syringe sterilized after a medicine is filled thereinto. As the pre-filled syringe, in addition to a one-solution type pre-filled syringe containing one kind of medicine, a two-chamber type pre-filed syringe containing two kinds of medicines separately in two chambers is known widely.
Most of the known two-chamber type pre-filled syringes have a construction shown in FIG. 5A. A cylindrical part 22 is partitioned into two chambers 25, 26 with two gaskets 23, 24; powdery or granular medicine (powder) A is sealed in the chamber 25 located at the front side of the cylindrical part 22; A solution B (solvent or solution for powdery or granular medicine sealed in chamber 25) is sealed in the chamber 26 located at the rear side of the cylindrical part 22. Otherwise, different kinds of solutions A and B are sealed in the chambers 25 and 26, respectively. FIG. 5 shows the case in which the powder is sealed in the chamber 25 and the solution is sealed in the chamber 26.
In using the two-chamber type pre-filled syringe shown in FIG. 5A, a cap is removed from the syringe and an injection needle is attached to the syringe. A plunger 27 installed on the gasket 24 is pressed. The gaskets 23, 24 and the solution B sealed in the chamber 26 located between both gaskets 23, 24 move forward. When the gasket 23 moves to a bypassing projection 28 formed radially outwardly at a portion of the cylindrical part 22, a gap (duct) 29 is formed between the peripheral surface of the gasket 23 and the inner peripheral surface of the cylindrical part 22. Through the gap (duct) 29, the solution B flows into the chamber 25 in which the medicine (powder) A and the solution B are mixed with each other (dissolution of the powder A into the solution B) to form a mixed solution. The plunger 27 is pressed forward further to move the gaskets 23, 24 forward further to inject the mixed solution to a patient through an injection needle installed at the front end of the cylindrical part 22.
For commercialization, normally, the solution which is used for injection is sterilized with high-pressure vapor. The powder and the granule are liable to melt or modify when they are sterilized with the high-pressure vapor. Thus, they are sterilized by a different treatment (aseptic filling treatment or the like). Therefore, as the conventional methods of producing the two-chamber type pre-filled syringe, shown in FIG. 5A, containing the powder sealed in the chamber 25 and the solution sealed in the chamber 26, the following two methods (1) and (2) are carried out:
Method (1): Referring to FIG. 6, with the solution B sealed in a cylindrical member 22b that composes the cylindrical part 22 by using the gaskets 23 and 24 or the gasket 23 and other sealing means (not shown), the solution B is sterilized with high-pressure vapor. Then, the powder A prepared separately is filled into a cylindrical member 22a that also composes the cylindrical part 22. Thereafter, the cylindrical member 22a and the cylindrical member 22b are connected in an aseptic atmosphere to compose the cylindrical part 22.
Method (2): Referring to FIG. 7, the cylindrical part 22c whose both ends are open is prepared. With the solution B sealed in the cylindrical part 22 by using the gaskets 23 and 24 or the gasket 23 and other sealing means (not shown), the solution B is sterilized with high-t pressure vapor. Then, the powder A prepared separately in an aseptic atmosphere is introduced into the cylindrical part 22c from the opening at the front end thereof. Thereafter, a nozzle 30 of the syringe is installed on the cylindrical part 22 at the front end thereof.
However, the methods (1) and (2) are complicated in the producing process and much time and labor are required. In particular, the method (1) requires a high technique in connecting the cylindrical member 22b sealing the solution B therein and the cylindrical member 22a sealing the powder therein to each other accurately.
The methods (1) and (2) are adopted to produce the two-chamber type pre-filled syringe sealing the solution that can be sterilized with high-pressure vapor in one chamber and the solution susceptible to heat in the other chamber. In this case, a similar problem occurs.
In the conventional two-chamber type pre-filled syringe shown in FIG. 5, let it be supposed that the plunger 27 is pressed too strongly by mistake while the powder A and the solution B are being mixed with each other (see FIG. 5B) and that the gasket 23 passes the bypass 28 and rapidly moves to a position forward therefrom. In this case, the gap (duct) 29 is closed before the entire solution B flows into the chamber 25 sealing the powder A. Consequently, the solution B and the powder A are not mixed completely with each other. Thus, much care should be taken in using the two-chamber type pre-filed syringe. That is, the two-chamber type pre-filled syringe is not easy to handle.
As another problem of the conventional two-chamber type pre-filled syringe shown in FIG. 5, the gasket 23 which has moved to the position of the bypass 28 during mixing of the solution B and the powder does not move to a rearward position of the cylindrical part 22 when the solution B flows into the chamber 25. Therefore, the chamber 25 should be designed to be large (length and diameter, namely, capacity) to flow the whole amount of the solution B into the chamber 25 and mix the solution B and the powder A sufficiently with each other in the chamber 25. Consequently, the entire two-chamber type pre-filled syringe becomes necessarily large. Further, the syringe consists of only the outer cylinder and the entire length of the syringe is long. Therefore, there is a room for improvement to allow the syringe to be compact to save energy and handled easily and conveniently in injection and discarding times. In the conventional two-chamber type pre-filled syringe shown in FIG. 5, there is one which is so designed that the gasket 23 and the gasket 24 are pressed to move toward the front end of the syringe while air is missing. It is possible that liquid leakage occurs in the syringe at the time of a mixing operation.
It is an object of the present invention to provide a two-chamber type pre-filled syringe that has a small number of component parts, can be produced in simple producing and assembling processes and with high productivity, and is safe and sanitary.
It is another object of the present invention to provide a two-chamber type pre-filled syringe which is capable of easily and sufficiently mixing two kinds of medicines separately sealed therein without requiring skill so that a mixed solution is used for injection to a patient or to a medical container.
It is still another object of the present invention to provide a two-chamber type pre-filled syringe that is compact to save energy and to be handled easily and conveniently in injection and discarding times.
It is still another object of the present invention to provide a two-chamber type pre-filled syringe in which while two kinds of medicines are being mixed with each other, liquid leakage does not occur.
It is still another object of the present invention to provide a two-chamber type pre-filled syringe in which the degree of resistance to a pressing force (in other words, injection resistance) is low when a mixture of two kinds of medicines is injected to a patient and which allows a mixed medicine to be discharged smoothly.
The object of this invention is to provide a pre-filled syringe that comprises an outer cylinder having a nozzle, at a front end thereof, sealed with a sealing member or a closed end and an opening formed at a rear end thereof; an inner cylinder movable forward and rearward in said outer cylinder, forming a first space between said inner cylinder and an inner side of said front end of said outer cylinder, and having an opening formed at each of front and rear ends thereof; a first gasket slidably accommodated in said inner cylinder in a liquid-tight state; a second gasket accommodated slidably in said inner cylinder in a liquid-tight state and located rearward from said first gasket and forming a second space between said second gasket and said first gasket; a plunger attached or attachable at a rear end of said second gasket; a third gasket installed at said front end of said inner cylinder or in the vicinity of said front end thereof such that third gasket is slidable in a liquid-tight state between said inner cylinder and said outer cylinder; a first medicine stored in said first space; and a second medicine stored in said second space, wherein said inner cylinder has a portion, formed at said front end thereof, for preventing said first gasket from slipping off from said opening formed at said front end of said inner cylinder; and a rib and/or a groove extending from an inner side surface of said front end of said inner cylinder in an axial direction of said inner cylinder to form a medicine duct for introducing said second medicine into said first space, when said first gasket moves to said front end of said inner cylinder; and said inner cylinder moves automatically toward said rear end of said outer cylinder owing to rise of a pressure inside said first space caused by a flow of said second medicine into said first space which occurs as a result of a movement of said second gasket and a movement of said first gasket to said front end of said inner cylinder caused by a pressing force applied to said second gasket.
Further, the object of this invention is to provide a pre-filled syringe that comprises an outer cylinder having a needle attached at a front end thereof and an opening formed at a rear end thereof: a slidable gasket accommodated in said outer cylinder; an inner cylinder movable forward and rearward in said outer cylinder, forming a first space between said inner cylinder and said slidable gasket, and having an opening formed at each of front and rear ends thereof; a first gasket slidably accommodated in said inner cylinder in a liquid-tight state; a second gasket accommodated slidably in said inner cylinder in a liquid-tight state at a position rearward from said first gasket and forming a second space between said second gasket and said first gasket; a plunger attached or attachable at said rear end of said second gasket; a third gasket installed at said front end of said inner cylinder or in the vicinity of said front end thereof such that said third gasket is slidable in a liquid-tight state between said inner cylinder and said outer cylinder; a first medicine stored in said first space; and a second medicine stored in said second space, wherein said inner cylinder has a locking portion, formed at said front end thereof, for preventing said first gasket from slipping off from said opening formed at said front end of said inner cylinder; and a rib and/or a groove extending from an inner surface of said front end of said inner cylinder in an axial direction thereof to form a medicine duct for introducing said second medicine into said first space, when said first gasket moves to said front end of said inner cylinder; and said inner cylinder moves automatically toward said rear end of said outer cylinder owing to a rise of a pressure inside said first space caused by a flow of said second medicine into said first space which occurs as a result of a movement of said second gasket and a movement said first gasket to said front end of said inner cylinder caused by a pressing force applied to said second gasket, and said outer cylinder has a rib and/or a groove extending axially from an inner surface of said front end of said outer cylinder to form a medicine duct for flowing a mixed solution formed by mixing said first medicine and said second medicine with each other in said first space to a position located forward from said slidable gasket, when said slidable gasket moves to said front end of said outer cylinder.